My website which once worked…type in website.com and it would automatically go to website.com/index.html where there is content, is now telling me “the website declined to show this webpage. Most likely causes - this website requires you to log in”

Judging from the fact that the question mentions IIS and ISAPI extensions, I’m not sure they’re a DreamHost customer at all. We certainly aren’t equipped to provide support for questions about other hosts.